Single and multiple deck conveyor dryers for reducing the moisture content of sheet materials, including green (or wet) wood veneer, wherein the material being dried is conveyed through a stationary drying chamber while heated gases are circulated through the drying chamber, are well-known in the art. Evaporation of moisture, inorganic compounds, and/or organic compounds (i.e. volatile organic compounds (V.O.C.'s)) from the material being dried causes a build-up of steam within the dryer, which may condense with carbon dioxide to form a corrosive liquid on the walls of the veneer dryer and on other equipment. Many metals corrode due to exposure to moisture and corrosion of metallic structures and surfaces of the dryer has been a major problem in the veneer drying art.
It is desirable to control the corrosion of metallic structures and surfaces of a wood veneer dryer to extend the lifetime of the dryer. To reduce corrosion, metallic structures and surfaces inside of veneer dryers may be made from or coated with corrosion-resistant alloys, such as stainless steel. However, corrosion-resistant alloys are typically expensive. Furthermore, moisture is not precluded from migrating into dryer panel cracks or missed welds not treated with the corrosion-resistant alloy. There is accordingly a need in the art for a wood veneer dryer wherein the metallic structures and surfaces inside the dryer susceptible to corrosion are protected.
Cathodic protection is known in the art to control the corrosion of a metal by making it the cathode of an electrolytic cell. The metal to be protected is connected to a more easily corroded “sacrificial” metal that acts as the anode. The sacrificial metal then corrodes instead of the protected metal. The driving force for the cathodic protection current is the difference in electrode potential between the anode and the cathode.
A cathodic protection system is essentially a closed electric circuit that requires an anode and cathode to be immersed in an electrolyte; hence, cathodic protection is not used to prevent atmospheric corrosion. Typically, the structure to be protected is immersed in a body of fresh or salt water or is buried in moisture-rich soil.
In practice, the main use of cathodic protection is to protect steel structures immersed in a body of water or buried in moisture-rich soil (for example, the exterior surfaces of pipelines, ships' hulls, jetties, foundation piling, steel sheet piling, offshore platforms, and the interior surfaces of water-storage tanks and water-circulating systems).
Due to high maintenance and installation costs, cathodic protection is typically considered to be prohibitively expensive for use with relatively small scale structures, such as wood veneer dryers. Use is further limited by the need for structures to be immersed in a body of water or buried in moisture-rich soil.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.